Ink jet printheads of the type manufactured using micro-electromechanical systems technology have been proposed in a construction using nozzle chambers formed in layers on the top of a substrate with nozzle chambers formed in the layers. Each chamber is provided with a movable paddle actuated by some form of actuator to force ink in a drop through the nozzle associated with the chamber upon receipt of an electrical signal to the actuator. Such a construction is typified by the disclosure in International Patent Application PCT/AU99/00894 to the Applicant.
The present invention stems from the realisation that there are advantages to be gained by dispensing with the paddles and causing ink drops to be forced from the nozzle by decreasing the size of the nozzle chamber. It has been realised that this can be achieved by causing the actuator to move the nozzle itself downwardly in the chamber thus dispensing with the paddle, simplifying construction and providing an environment which is less prone to the leakage of ink from the nozzle chamber.
Furthermore, Applicant has identified that it would be useful to incorporate a mechanism whereby ink ejection ports could be kept clear of obstructions, such as dried ink or paper dust.